1. Field of the Invention
The invention relates to industrial ovens for drying, finishing, or heat-treating relatively large products and, more particularly, relates to an industrial oven having expansion joints permitting both lateral and longitudinal movement between intersecting structural components thereof resulting from expansion of those or other components.
2. Discussion of the Related Art
Industrial ovens are well-known in the art for drying, finishing, and/or heat-treating a wide variety of items of many different sizes. Depending on the application, these ovens typically are heated to temperatures of up to about 800.degree. F., and are very large--on the order of 20-100' long by 20-30' wide by 10-20' high.
The typical oven includes a floor assembly, front, rear, left, and right side walls, and a roof assembly. At least the walls and the roof assembly typically take the form of inner and outer metal shells separated from one another by a layer of insulation. The extreme temperature changes encountered by these ovens, coupled with their relatively large size, leads to significant expansion of not only the inner and outer shells, but also of the steel components of their structural framework. The problem of accommodating structural expansion of the shells is addressed, for example, in U.S. Pat. No. 4,311,460 ('460 patent) to Lauersdorf and U.S. Pat. No. 5,259,758 to Lauersdorf. These patents also incorporate measures to permit longitudinal expansion of portions of an oven's structural steel framework. For instance, the Lauersdorf '460 patent employs expansion slots at the joints between girts of the walls and between the vertical columns on which the girts are supported. Similarly, U.S. Pat. No. 4,764,108 to Carthew and U.S. Pat. No. 5,475,958 to Josefsson both disclose modular ovens having a plurality of longitudinally-aligned sections each of which is connected to an adjacent section at an expansion joint, permitting longitudinal expansion of the adjacent sections relative to one another. However, none of these patents incorporates measures to permit relative lateral and longitudinal movement between intersecting support beams of its structural steel framework resulting from expansion of one or both of the intersecting beams and/or other components of the oven. This limitation proves problematic in oven designs in which some heated beams, such as roof purlins or floor support members, are supported on and run perpendicularly with respect to other beams, such as roof trusses or oven base support beams. It is possible that either or both of a pair of connected intersecting beams can expand from between 1" to 2" during operation of the oven. No prior known oven design incorporates measures to accommodate this degree of relative bi-directional movement between two intersecting support beams.